The present application claims priority to Japanese Application No. P11-002094 filed Jan. 7, 1999, which application is incorporated herein by reference to the extent permitted by law.
1. Technical Field
The present invention relates to a solid-state imaging device to be applied to an electronic endoscope or the like, particularly to a solid-state imaging device constituted so that a circuit board and electronic components mounted on the circuit board can be set in the projection area of a not-packaged solid-state imaging chip including a CCD and thereby, a solid-state imaging unit can be downsized and thus, the outside diameter of the front end of the electronic endoscope can be decreased.
2. Description of the Related Art
In recent years, various types of electronic endoscopes respectively using a solid-state imaging chip such as a charge-coupled device (CCD) as an imaging means and the like are proposed, of which the solid-state imaging chip is embedded in the front end of a tube inserted into the body of an endoscope. Therefore, a thinner and shorter tube front end is preferable in order to ease the pain of a patient. However, in order to decrease the tube in diameter and length, how the solid-state imaging chip can be downsized has been an important technical problem.
A conventional endoscope using a solid-state imaging chip is disclosed in U.S. Pat. No. 2,607,542 (Japanese Patent Laid-Open No. 313970/1988). FIG. 1 shows a composition of one example of the endoscope. Electronic components 41 and 42 are mounted on one plane (upper plane) and the other plane (lower plane) of a horizontally-set circuit board shown by symbol 40. A not-packaged solid-state imaging chip 43 is perpendicularly combined with one plane of the front end of the circuit board 40 separately from the electronic component 41. Moreover, an end of the circuit board 40 and a not-illustrated bonding pad provided in the front surface of the solid-state imaging chip 43 are electrically connected with each other by a bonding wire 44. Furthermore, a signal cable 45 is connected to the rear end of the circuit board 40.
Meanwhile, the front surface of the solid-state imaging chip 43 is airtightly covered with a cover glass 46 and optical lenses 48, 49, and 50 supported by a lens barrel 47 are arranged in front of the cover glass 46 so as to oppose the optical axis of the solid-state imaging chip 43. Moreover, the above-mentioned respective components are covered with a sheath 51 and the space in the sheath 51 is filled with a molding material 52.
With the endoscope constituted as mentioned above, however, because the end surface of the circuit board 40 is connected with the solid-state imaging chip 43 by the bonding wire 44, a space for bonding is required in the outside-diameter direction of the solid-state imaging chip 43. Therefore, it cannot be avoided that the outside diameter of the front end of the endoscope increases by a value equivalent to the size of the space and this prevents the diameter from decreasing.
The present invention is implemented to solve the above problems and its object is to provide a solid-state imaging device capable of downsizing an imaging unit and thereby, further decreasing the diameter at the front end of an endoscope.
The present invention provides a solid-state imaging device comprising:
a not-packaged solid-state imaging chip;
a circuit board which is combined with the plane on the opposite side of the imaging plane of the solid-state imaging chip and on which electronic components are mounted; and
a connection means constituted of a film on which a wiring pattern for electrically connecting a bonding pad provided in the outer peripheral portion of the imaging plane of the solid-state imaging chip with a bonding pad provided in the circuit board is formed; wherein
the electronic components are mounted on the stepped portion of the circuit board formed lower than the outline of said solid-state imaging chip and a signal cable is connected to an end of said stepped portion so that said electronic components mounted on said circuit board and the terminal portion of the cable are arranged in the projection area of said solid-state imaging chip.
Moreover, the present invention provides another solid-state imaging device comprising:
a not-packaged solid-state imaging chip;
a circuit board which is combined with the plane on the opposite side of the imaging plane of the solid-state imaging chip and on which electronic components are mounted; and
a connection means constituted of a bonding wire for electrically connecting a bonding pad provided in the outer peripheral portion of the imaging plane of said solid-state imaging chip with a bonding pad provided in the circuit board; wherein
said electronic components are mounted on the stepped portion of the circuit board formed lower than the outline of said solid-state imaging chip and a signal cable is connected to an end of said stepped portion so that said electronic components mounted on said circuit board and the terminal portion of the cable are arranged in the projection area of said solid-state imaging chip.